How to Publish Exchange Server 2010 POP3 and IMAP on ISA Server

As we know, POP3 is used by the clients so that they can connect to their POP3 server and can download the e-mails to their application.

To protect Microsoft Exchange Server 2010 POP3 and IMAP connection, we can use Internet Security and acceleration (ISA) Server 2006 where external clients will not have direct have access to the POP3/IMAP services and also, all communication with your Internal servers will be secured. Communications between Internet POP3/IMAP clients to ISA Server and Client Access servers all are encrypted by using the SSL.

When external clients try to access published POP3/IMAP applications on ISA server, their request is first accepted by the ISA server. ISA server decrypts their requests, end the client connections and make a new connection with the published server by using SSL. In this way, published servers are never directly exposed to the internet clients.

To secure the communication between internet clients and ISA server, we need to install a server certificate on the ISA server. We can do this in two ways:-

1. Install a certificate on the ISA server issued by the public Certificate Authority, or

2. If using private CA, install root certificate from the private CA to the client computers.

To publish POP3 and IMAP4 on ISA Server 2006, we need to create a web listener and publishing rule on the ISA server